(CNN)Three Colorado sheriff's deputies have been killed in separate shootings over a span of 37 days -- and the state's governor says he's had enough.

Gov. John Hickenlooper pleaded for a stop to the violence, which also has seen other officers and bystanders wounded.

"With the recent loss of now three deputies and many others injured, there's no denying the grave impact this sequence of shootings is having on our state," Hickenlooper said Monday after an El Paso County sheriff's deputy was shot dead while investigating a vehicle theft.

"We will once more come together to provide sympathy and strength for the deputy's loved ones and pray for the recovery of those injured; however, we also must come together and say enough is enough."

Here are details of the three killings, which stretch back to New Year's Eve:

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December 31: Deputy Zackari Parrish

On the morning of December 31, several Douglas County sheriff's deputies went to a Denver-area apartment complex after someone called police to say a man "might be having a mental breakdown there," the sheriff's office said.

Deputy Zackari Parrish

The man's roommate gave the deputies a key to the apartment in Highlands Ranch, about 20 miles south of Denver.

Four deputies were shot. One of them -- Zackari Parrish, a 29-year-old father of two -- was mortally wounded.

About 90 minutes later, a police tactical team arrived and exchanged gunfire with Riehl. A Castle Rock police officer was injured; Riehl was shot and killed.Two civilians also were shot as the incident unfolded.

Police didn't immediately release a suspected motive. But several law enforcement agencies had been aware weeks beforehand that Riehl, a 37-year-old former Army reservist, was accused of writing harassing or suspicious messages online, including threats to police officers, officials said.

At a candlelight vigil for Parrish, his mourning widow pledged to honor his memory.

"And I will raise these girls to love you," Gracie Parrish said, referring to their daughters, as she wept.

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When the deputies followed the man behind a home, the man pulled out a handgun and fired, hitting Gumm in the chest, a sheriff's spokeswoman said.

Gumm, 31, died of the wound. The alleged shooter was taken into custody, officials said.

The five-year veteran of the force, who left behind a wife, had just been recognized for his work. A mother had sent the sheriff's office a letter of gratitude about him.

"She was moved so much by the level of service that deputy Gumm provided to her son that she took the time to reach out and make sure that we knew," Sheriff Michael McIntosh said. "You can imagine that over the course of the last five years, there's a lot of stories like this about Deputy Gumm."

February 5: Deputy Micah Flick

Micah Flick was marking his 11th anniversary as a sheriff's deputy in Colorado's El Paso County when he and some colleagues were looking into a report of a vehicle theft on Monday. It would be his last call.

Deputy Micah Flick

Flick, 34, was shot and killed -- and three other law enforcement officers were shot and injured -- during a struggle with a suspect in Colorado Springs, authorities say.

The suspect died, police said, without immediately elaborating.

Flick leaves a wife and 7-year-old twins.

"Deputy Flick was an outstanding member of our agency, and he will be missed," El Paso County Sheriff Bill Elder said.